Aluminosilicates containing cations capable of exchanging which possess the capacity of sequestering ions causing water hardness are known. Such substances can be easily obtained, for example, by reaction of water-soluble silicates with water-soluble aluminates in the presence of water.
For this purpose, aqueous solutions of the starting materials can be mixed with each other or when one component is present as solid, it can be caused to react with the other which is present as an aqueous solution. When both components are in the solid state, they can be mixed in the presence of water to obtain the desired aluminosilicates. Such aluminosilicates can also be prepared by causing Al(OH).sub.3 or Al.sub.2 O.sub.3 to react with alkali metal silicate solutions. Process for the preparation of these aluminosilicates are described, for example, in copending U.S. patent application Ser. No. 458,306, filed Apr. 5, 1974, now abandoned.